I assume it depends where you are from and at what season you want to feed them.
In Europe it is not so much common to feed birds in the summer. In rural areas they would prefer to hide and would find enough food, in urban areas they would not be fed enough to live there, and the doves and sparrows which live there, do not need to be fed separately.
So in Europe the most people who want to feed birds, do so in winter time. When snow covers the grounds, the birds are not easy able to find enough food. Then bird feeders attract the most attention.
In general one does not need to install road signs, saying "Fly in". Some birds will find the food by accident and others will follow. But to increase this, first one can spread some (small) amount of food in a bigger range around the bird feeder, so the "by accident" increases. But be careful, food at the ground could also attract rats, you do not want.
Some birds are vegetarians (some only in winter), they prefer seeds in any size. Small would be poppy, rape, hemp, sesame, line, millet and grass seed. Bigger are sunflower (with or without peel), peanut, walnut, hazelnut (nuts without peel), raisins and even half of apples (you should warm apples up inside from time to time so they not freeze).
Other birds like to eat insects even in winter. To attract them you can try dried meal-worm (wren and jay adore them) and other dried insects one can find for reptile-pets (but be careful to avoid "added vitamins", they would suit reptiles, but not birds).
Also the place to feed is important. To avoid birds as doves or crows one can add a wide sturdy mesh, smaller birds pass through, but bigger can't. The feeder should pretend to be a safe place, so not at the ground (cats), between some twigs (hawks). If you want to place it in front of your window, you can add some "twig" between window and feeder, so you can see them, but they feel safe. Some birds like to peck from a surface, others like to hold at the food, hanging down. Some like to eat at the feeder, some like to carry one seed away, eat and take the next seed away.
Because you mentioned suet: At my country there is spreading a disease in hogs, also affecting pigs, which can be carried from all pig parts. So be careful you use suet from cows only, or use coconut oil (palm oil has also some environmental issues...).
So in conclusion you should try different variations and see, what works best. More different you offer, more different birds will be attracted.
